New York doctors who accepted speaking fees, honoraria, meals and other forms of payment from opioid manufacturers started writing more prescriptions for the narcotic painkillers, according to an analysis from the New York State Health Foundation.

When comparing physicians in similar specialties who historically prescribed similar amounts of opioids, the researchers found that those who started accepting pharma payments increased their opioid prescribing rates significantly more over time than those who did not.

"The prescribing of opioids has been going down now for a few years and New York state has implemented some safeguards," said Mark Zezza, director of policy and research at the New York State Health Foundation and one of the report's authors. "But we're still seeing quite large payments being made to doctors and other research has shown even small payments like a lunch can influence prescribing patterns."

Zezza used the CMS Open Payments database to find out which prescribers received opioid-related payments. He then used Medicare Part D expenditures on opioids by provider as a proxy for the amount of opioids each doctor prescribed.

A group of doctors who started receiving opioid-related payments in 2014 increased their prescribing rates by 37.2% from the previous year and another 24.7% between 2014 and 2015, according to the report. By contrast, a group of similar doctors who did not receive opioid-related payments in those years increased their prescribing by 15.6% in 2014 and just 1.9% in 2015.

Pharmaceutical companies paid a total of $196.4 million to New York doctors during the study period of August 2013 to December 2015. During that time 3,389 New York doctors received $3.6 million in payments specifically related to opioids. Among those doctors, the average total amount received was about $1,000.

The largest share of payments, 73.1%, came from speaking fees and honoraria. However, the most frequent payments, 87.7%, were for food and beverage.

About $1.9 million—more than half of the opioid-related payments made to physicians during the study period—came from Insys Therapeutics, which manufactures Subsys, an oral spray of fentanyl.

In March, five New York doctors were charged with taking kickbacks from the company in exchange for prescriptions, Reuters reported. Other doctors have already been convicted for participating in the scheme. But seven former executives and managers at Insys who have been accused of bribing doctors have pled not guilty.

Insys did not respond to a request for comment on whether it has changed its practices.

Purdue Pharma, which manufactures OxyContin and is involved in lawsuits alleging that it has misrepresented its products, made $591,611 in opioid-related payments to New York doctors during the study period. It reached 1,915 doctors, the most of any of the top five pharma companies making such payments during the study period.

Purdue said in February that it cut its sales force in half and planned to stop promoting opioids to prescribers, Reuters reported.

Teva Pharmaceuticals, Janssen Pharmaceuticals and Depomed were also in the top five in terms of payments to physicians.

While lawsuits against opioid manufacturers are moving ahead, Zezza said the next step for researchers is to prove that the opioids prescribed by doctors receiving payments were inappropriate to treat their patients' conditions.

"It really does raise additional concerns about potential conflicts of interest and policymakers should make it a priority to do that next level of research," said Zezza.

Crain’s New York Business is the trusted voice of the New York business community—connecting businesses across the five boroughs by providing analysis and opinion on how to navigate New York’s complex business and political landscape.